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Posted: Fri Jun 22, 2007 5:29 pm
by Maschinengeist
Hi evildragon

I don't have any motherboard in stock. I rarely keep those parts (but will someday. Another work in progress). But I'll check around and will contact my part suppliers to see if one got one available.

As for test, you can persorm a few on the ICs with a digital multimeter to make sure its in/out (among other things) are accurate. It's important to follow the pinout, otherwise you'll fry the chip. Please refer to the IC Block Diagram in the Service Manual.

You can also get yourself a basic logic probe off eBay for less than $20.

Note: the previous message was intended to dachsis. Sorry for the confusion.

Posted: Fri Jun 22, 2007 5:31 pm
by evildragon
ok, i'll give those tests a shot then with my multimeter when the problems creeps up again... (continuity test, correct?)

i'm also going to find an in-circuit cap tester too..

DX7IIFD won't do anything

Posted: Fri Jun 22, 2007 6:27 pm
by dachsis
evildragon wrote:ok, i'll give those tests a shot then with my multimeter when the problems creeps up again... (continuity test, correct?)

i'm also going to find an in-circuit cap tester too..
on IC s you are ckg the in/out values, right ?
thanks for the serv contact, these are invaluable.
No more old Yamaha serv shoppes to buyout and reap bounties.

Posted: Fri Jun 22, 2007 6:54 pm
by evildragon
http://blackevilweredragon.spymac.com/dx72.jpg

http://blackevilweredragon.spymac.com/dx73.jpg

one of the IC block diagrams.. im actually curious which in and out too... i've never messed with logic gates before (i've wanted to learn)

Posted: Fri Jun 22, 2007 9:17 pm
by Maschinengeist
VCC = Supplied Voltage = Positive

VSS = Supplied Voltage = Negative

After that, it's only a matter to follow the schematics, indicating the in and the out of the pins.

More than a continuity test, it's a (basic but efficient) way to narrow down what part of the chip is bugging down.

PLEASE RESPECT THE POLARITY AND PAY EXTREME ATTENTION TO THE PIN CONFIGURATION OR YOU'LL FRY THE CHIP AND QUITE PROPABLE DAMAGE THE SYNTH IN AN UNPLEASANT WAY.

Good luck!